System and method for electroporating a sample

ABSTRACT

A system and method are described for electroporating a sample that utilizes one or more sets of electrodes that are spaced apart in order to hold a surface tension constrained sample between the electrodes. The first electrode is connected to the lower body of the system while the second electrode is connected to the upper body. Both electrodes are connected to a pulse generator. Each electrode has a sample contact surface such that the first electrode and the second electrode may be positioned to hold a surface tension constrained sample between the two sample contact surfaces and the sample may receive a selected electric pulse.

TECHNICAL FIELD OF THE INVENTION

The present disclosure relates in general to systems and method forprocessing biological samples and more particularly to anelectroporation system and method of use thereof.

BACKGROUND OF THE INVENTION

Gene silencing using small interfering RNAs (siRNAs) has become apowerful method for studying gene function. The use of siRNAs oftenaccelerates applications such as target validation, gene discovery,tissue engineering and gene therapeutic approaches. siRNAs are oftenused by researchers to reduce the expression of specific genes inmammalian cells. Researchers may design siRNAs or purchase validatedsiRNAs for their target of interest and transfect them into culturecells. Human primary cells are often desired for such experimentsbecause they are more similar to their in vivo counterparts than areimmortalized cells. However, common chemical-based transfection methodsthat work well for cell lines often fail to transfect primary cells.

One technique that has been used with considerable success to deliversiRNA to cells (including primary cells) is electroporation.Electroporation involves applying an electric field pulse to cells toinduce the formation of microscopic pores (electropores) in the cellmembrane allowing molecules, ions, and water to traverse thedestabilized cell membrane. The transfer of nucleic acids to cells byelectroporation is an effective method for achieving high efficiencytransfections in vitro and in vivo. Under specific pulse conditions, theelectropores reseal and the “electroporated” cells recover and continueto grow.

Successfully delivering functional siRNA to cells typically requiresthat several optimum electroporation conditions be determined. Todetermine optimal electroporation conditions, a comprehensive set ofdata is usually generated from a collection of different transfectionconditions including: testing various electrical wave-forms, types ofelectroporation buffers, different temperatures, and cell densities.Careful examination of these parameters for a new cell type typicallyrequires lengthy processing times using standard cuvette-basedelectroporation methods.

In some electroporation environments successful delivery and cellviability depend on multiple electrical parameters such as: fieldstrength (primarily voltage in relation to gap width), pulse length, andnumber of pulses. Determining the optimum electroporation conditions fordelivering siRNA is typically a lengthy and costly process. Additionalexperimentation may then be carried out to test multiple differentsiRNAs in various amounts to modulate the target gene (or genes) to adesired level of expression.

A significant drawback to electroporation is the format in which it isconducted. Commercially available electroporation instruments use samplecuvettes and require significant amounts of preparation. This limits thenumber and types of experiments that can be performed, incurs theexpense of using a specialized cuvette to deliver the desired pulse tothe sample, and requires significant time and effort to deposit sampleswithin the cuvettes, deposit the cuvettes in an appropriate apparatus,and to remove the electroporated sample from the cuvette.

SUMMARY OF THE INVENTION

Therefore a need has arisen for a system and method for facilitating theelectroporation of a sample that does not require a cuvette.

A further need has arisen for a system and method for efficientlyelectroporating multiple samples.

In accordance with teachings of the present disclosure, a system andmethod are described for electroporating a sample that reduces oreliminate drawbacks associated with previous electroporation systems andmethods. An electroporation system is disclosed that includes one ormore sets of electrodes that are spaced apart in order to hold a surfacetension constrained sample between the electrodes. The system mayinclude multiple sets of electrodes in order to allow multiple samplesto be electroporated simultaneously.

In one aspect an electroporation system is disclosed that includes ahousing having a lower body and an upper body. A first removableelectrode is connected to the lower body. A second removable electrodeis connected to the upper body. Both electrodes may receive an electricpulse from a pulse generator. Each removable electrode has a samplecontact surface and the first removable electrode and the secondremovable electrode may be positioned such that a surface tensionconstrained sample may be confined between the two sample contactsurfaces.

In another aspect, an electrode array is disclosed that includes anelectrode base that may conductively couple to an electroporation body.The electrode base has multiple sample contact surfaces formed thereon.The electrode is able to receive a pulse from a pulse generator and eachof the sample contact surfaces is sized to hold an electroporationsample.

In another aspect an electroporation system includes a housing that hasa lower body and an upper body. A first electrode array is attached tothe lower body and a second electrode array is attached to the upperbody. The first electrode array has multiple lower sample contactsurfaces and the second electrode array has multiple upper samplecontact surfaces that correspond to the multiple lower sample contactsurfaces. The lower body and the upper body are positioned to confine asurface tension constrained sample between each of the correspondingpairs of upper contact surfaces and lower contact surfaces. Theelectrode arrays may receive an electric pulse from a pulse generator tofacilitate the electroporation of the samples.

In yet another aspect, a method for electroporating a sample comprisespositioning the upper body of an electroporation apparatus in an accessposition. Samples that are to be electroporated are then deposited onthe multiple lower sample contact surfaces of the electrode array of thelower body. The upper body is then moved into an operational positionsuch that corresponding upper sample contact surfaces contact thesamples resting on the lower sample contact surfaces. Each sample isconfined between an upper sample contact surface and a lower samplecontact surface by the surface tension of each sample. A selectedelectric pulse is then passed between the lower electrode and the upperelectrode, sufficient to electroporate each sample.

The present disclosure includes a number of important technicaladvantages. One technical advantage is to provide electrode pairs withcontact surfaces positioned to confine a surface tension constrainedsample therebetween. This allows for electroporation to be conductedwithout the use of cuvettes. Another technical advantage is to provideelectrode arrays that have multiple contact surfaces formed thereon.This allows for multiple samples to be electroporated simultaneously.Additional advantages will be apparent to those of skill in the art inthe description, FIGURES, and claims below.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments and advantagesthereof may be acquired by referring to the following description takenin conjunction with the accompanying drawings, in which like referencenumbers indicate like features, and wherein:

FIG. 1 is an electroporation system shown in an access position;

FIG. 2 is an electroporation system shown in an operational position;

FIG. 3 is an electrode with a sample deposited thereon;

FIG. 4 shows a surface tension constrained sample confined between twoelectrodes;

FIG. 5 shows an electroporation system including a pulse generator and amonitoring system;

FIG. 6 is an electrode pair having corresponding concave and convexsurfaces;

FIG. 7 is an electrode pair having corresponding concave and convexsurfaces;

FIG. 8 is an eight sample electroporation system shown in an accessposition;

FIG. 9 is an eight sample electroporation system shown in an operationalposition;

FIG. 10 is an electrode array according to teachings of the presentdisclosure;

FIG. 11 is shows an electrode array interfacing with the lower body ofan electroporation system;

FIG. 12 shows an eight sample electroporation system in an operationalposition according to teachings of the present disclosure;

FIG. 13 shows an eight sample electroporation system in an accessposition according to teachings of the present disclosure;

FIG. 14 shows a ninety-six sample electroporation system in an accessposition according to teaching of the present disclosure;

FIG. 15 shows a ninety-six sample electroporation system in anoperational position according to teachings of the present disclosure;

FIG. 16 shows an electroporation system according to teachings of thepresent disclosure;

FIG. 17 shows a conductive slide according to teachings of the presentdisclosure; and

FIG. 18 shows an electroporation system and conductive slide accordingto teachings of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments and their advantages are best understood byreference to FIGS. 1 through 15, wherein like numbers are used toindicate like and corresponding parts.

The novel systems described herein offer significant improvement in thepractical application of electroporation and thereby promote the use ofsiRNA molecules to more cell types and to researchers previouslyunfamiliar with electroporation. The electroporation systems aredesigned to constrain a sample based on the sample's surface tensionrather than hardware geometry alone (as compared with cuvette-basedelectroporation methods). The disclosed systems simplify the overallelectroporation process and promote the more rapid determination ofoptimum electroporation conditions with reasonable cost and time.

Now referring to FIG. 1, an electroporation system 10 is shown.Electroporation system 10 includes housing 12 that generally includeslower body 14 and upper body 16. Lower body 14 and upper body 16 areboth constructed of nonconductive materials such as, for example acetalplastic. In the present embodiment, upper body 16 is pivotally connectedto lower body 14 at pivot 34. In the present embodiment this allowsupper body 16 to rotate between a generally vertical access position, asshown, and an operational position as shown in FIG. 2.

Electroporation system 10 further includes first electrode 18 insertedwithin electrode aperture 17 formed in lower body 14 as well as secondelectrode 22 disposed within electrode aperture 21. First electrode 18may also be referred to as a “removable electrode”, “disposableelectrode” or a “lower electrode” herein. Second electrode 22 may alsobe referred to as a “removable electrode”, “disposable electrode” or an“upper electrode” herein. First and second electrodes 18 and 22 arepreferably removable from electrode apertures 17 and 21 such that theymay be cleaned, replaced, or disposed of following an electroporationoperation. In alternate embodiments, first electrode 18 and secondelectrode 22 may be selectively fixed to lower body 14 and upper body 16using any suitable attachment mechanism that also allows first electrode18 and second electrode 22 to be conductively connected to a pulsegenerator.

In the present embodiment first electrode 18 has a generally cylindricalbody and a sample contact structure 19 formed at one end thereof.Similarly, second electrode 22 includes a sample contact structure 23,including second sample contact surface 24 (which may also be referredto as the upper sample contact surface), formed on one end thereof. Theend of sample contact structure 23 that extends from upper body 16 formssecond sample contact surface 24 (which may also be referred to as uppercontact surface).

In the present embodiment first and second sample contact surfaces 20and 24 are formed to correspond with one another, having substantiallyidentical shapes. First and second sample contact surfaces 20 and 24have substantially circular in shape and are substantially flat. Firstsample contact surface 20 is preferably sized to have a volume of sampleappropriate for electroporation deposited thereon. Second sample contactsurface 24 is correspondingly sized to contact the sample for carryingout the electroporation operation. In the present preferred embodimentfirst sample contact surface 20 is sized to hold a sample betweenapproximately ten microliters and two hundred microliters. In oneembodiment, this corresponds to first sample contact surface 20 having adiameter between approximately two millimeters and approximately twelvemillimeters. Additionally, the sample size supportable forelectroporation between first sample contact surface 20 and secondsample contact surface 24 is further dependent upon gap-width betweenthe contact surfaces during electroporation. As the gap width increases,the sample size supported between first sample contact surface 20 andsecond sample contact surface 24 increases. However, if gap widthincreases too much, the surface tension of the sample will be unablesupport the sample between the contact surfaces. Accordingly, theappropriate upper limit of gap width between first contact surface 20and second contact surface 24 will vary depending on the surface areaand geometry of contact surfaces 20 and 24 and the properties of thesample being processed. In preferred embodiments, electroporation sample10 may support a gap width between first contact surface 20 and secondcontact surface 24 in the range of 0.01 millimeter and approximately ten(10) millimeters.

First electrode 18 and second electrode 22 further include contacts 26and 30 to facilitate a conductive connection with a pulse generator (asshown in FIG. 5). Contacts 26 and 30 are formed to align with accessapertures 28 and 32 formed in lower body 14 and upper body 16,respectively. Connectors (not expressly shown) associated with a pulsegenerator may pass through access apertures 28 and 32 to contact firstelectrode contact 26 and second electrode contact 30. This preferablyallows for fast and convenient connection and disconnection with firstelectrode 18 and second electrode 22 which is particularly convenientfor in instances where electrodes 18 and 22 are frequently removed andreplaced.

Now referring to FIG. 2, electroporation system 10 is shown in anoperational position. As shown, upper arm 16 has been rotated in thedirection of arrow 40 to an operational position where first samplecontact surface 20 and second sample contact surface are insubstantially vertical alignment and slightly displaced from one anotherin order to hold a surface tension constrained sample therebetween.

In alternate embodiments, the access position may include anyappropriate position where upper body 16 is positioned away from lowerbody 14. This may include an access position (not expressly shown) whereupper body 16 is simply raised vertically with respect to lower arm 14such that sample contact surface 20 is accessible to a user of system10.

In the present embodiment, as upper body 16 (which may also be referredto as a movable arm assembly or a swing arm herein) is moved in thedirection of arrow 40, upper body 16 is moved to allow second samplecontact surface 24 to substantially fully contact a sample resting onfirst contact surface 20. This typically requires that second contactsurface 24 is positioned in slightly closer proximity to first contactsurface 20 than in the operational position, thereby “pushing down”slightly on the sample. This position (not expressly shown) may bereferred to herein as the “sample contact position”. The sample contactposition ensures that both sample contact surfaces 20 and 24 are incontact with the sample. The upper arm is then moved to the operationalposition (as shown in FIG. 4) wherein the surface tension of the sampleacts to confine the sample between the first contact surface 20 and thesecond contact surface 24 without the use of a cuvette.

After a samples is confined between first contact surface 20 and secondcontact surface 22, an electric pulse is passed through the sample. Theelectrical field generated between the two facing sample contactsurfaces 20 and 24 mediates reversible membrane permeabilization of thesuspended cells within the sample, preferably allowing one or moredesired elements such as, for example, a nucleic acid, protein or otherbiologically active compound, siRNA, messenger RNA (mRNA), or any otherdesired molecule included within the sample solution to traverse intothe cells. After the electric pulse is complete, the cell membranesrestabilize with the desired molecules delivered therein. Upper body 16may then be moved back to the access position. This step is typicallyperformed slowly such that the sample may disengage from second samplecontact surface 24 and rests completely on first sample contact surface20. The sample may then be removed from first sample contact surface 20,such as via a pipette, for subsequent use such as being transferred intoa culturing vessel. In the event that some of the sample remainsattached to second contact surface 24, such sample may also be removedby pipette.

In some embodiments, electrodes 18 and 22 may then be cleaned to removeany residual sample therefrom. In other embodiments, electrodes 18 and22 are preferably removed and disposed of and replace with replacementelectrodes. Replacement electrodes may be identical to electrodes 18 and22. Alternatively, replace electrodes may vary in the size and/or shapeof the contact surfaces 20 and 24. In one embodiment, a series ofelectrode pairs may be provide that have a range of sample contactsurface sizes in order to facilitate electroporation of various sizedsamples. Additional alternative embodiments of electrode pairs are shownin FIGS. 6 and 7.

Electroporation system 10 provides a convenient and efficientelectroporation apparatus that may be particularly suited forlaboratories and other users that do not require a high throughput ofsamples, but regularly need for transfection of samples. Electroporationsystem 10 facilitates such transfection without the use of cuvettes.

FIG. 3 shows first electrode 18 when electroporation system is in anaccess position. As shown, sample 50 is deposited on sample contactsurface 20 atop sample contact structure 19 of first electrode 18. Bothadherent and suspended varieties of multiple primary and culturedimmortalized cell types may be examined. These may include, but are notlimited to HUVEC, hMSC, PC12, human B or T cells, human or mouseNeuronal, Hela, MCF-7, K562, or Jurkat cells. In Some preferredembodiments the siRNAs to be used may preferably target housekeepinggenes or other highly expressed genes, or any gene or regulatory elementrelevant to a user.

FIG. 4 shows the sample contact structure 19 of first electrode 18 andsample contact structure 23 of second electrode 22 in an operationalposition. The surface tension of sample 50 confines it between firstsample contact surface 20 and second sample contact surface. As shown,first sample contact surface 20 and second sample contact surface 24 arepositioned a selected distance 52 which may also referred to as gapwidth, apart from each other.

FIG. 5 shows an electroporation system including pulse generator 102 anda monitoring system 104. As shown, electroporation device 100 isconductively couple to pulse generator 102. Pulse generator 102selectively provides an electric pulse to one or more samples heldwithin electroporation devices 100. Any suitable pulse generator may beemployed including, for example, a BTX Electro Square Porator ECM 830, aBioRad GenePulser Xcell, and a Cyto Pulse PA/4000S pulse generator.Pulse generator 102 is preferably connected to monitoring system 104. Inthe present embodiment, monitoring system is a computer system thatincludes software to set, manage and archive the applied waveformsproduced by pulse generator 102.

FIGS. 6 and 7 shows electrode pairs 120 and 130, respectively. Electrodepair 120 includes first electrode 122 and second electrode 124. Firstelectrode 122 includes contact 26 for connecting with a pulse generatorand a concave sample contact surface 126. Second electrode 124 includeselectrode contact 30 for connecting with a pulse generator and convexsample contact surface 128. Concave sample contact surface 126 forms abowl a the end of electrode 122 for depositing a sample. Convex samplecontact surface 128 is formed to substantially correspond with concavesample contact surface 126.

Electrode pair 130 includes first electrode 132 and second electrode134. First electrode 132 includes contact 26 for connecting with a pulsegenerator and a concave sample contact surface 136. Second electrode 134includes electrode contact 30 for connecting with a pulse generator andconvex sample contact surface 138. Concave sample contact surface 136forms a bowl a the end of electrode 132 for depositing a sample. Convexsample contact surface 138 is formed to substantially correspond withconcave sample contact surface 136. As shown, convex sample contactsurface 136 forms a substantially hemispherical bowl and concave samplecontact surface 138 forms a substantially hemispherical protrusion.

FIG. 8 shows an eight sample electroporation system depicted generallyat 200 shown in an access or open position. Electroporation system 200includes a housing 210 made up of lower body 212 (which may also bereferred to as the “base”) and upper body 214 (which may also bereferred to as the “top”). First electrode array 216, which may also bereferred to as an “lower” electrode array, is preferably coupled tolower body 212. First electrode array includes array body 217 with eightlower electrodes 220 formed thereon. Each of the lower electrodes 220further includes a lower electrode sample contact surface 222. Secondelectrode array 218 is preferably coupled to upper body 214. Secondelectrode array includes array body 219 with eight upper electrodes 224formed thereon. Each of the upper electrodes 224 includes an upperelectrode sample contact surface 226.

Upper body 214 is preferably formed to enshroud and prevent physicalaccess to lower electrode array 216 and upper electrode array 224 whenupper body is moved to the operation position (as shown in FIG. 9). Inthe present embodiment, upper body 214 is pivotally connected with lowerbody 212 along pivot 230. Upper body further include interlock fangs 232that protrude from upper body 214. Interlock fangs 232 correspond tointerlock spring contacts 234. Fangs 232 are preferably inserted intoand jumper together the two lower contact springs 234 when upper body214 is moved into an operational position. Additionally, spring plungers236 extend from lower body 212. Spring plungers 236 support top 214during electroporation so that electrodes 220 and 224 are preciselyspaced apart and are substantially parallel. Spring plungers 236 mayfurther depress down when pressure is applied to top 214 such that upperelectrodes 224 may brought sufficiently close to contact sample that isresting on lower electrodes 220. Contacting the sample preferably formsa resilient surface tension constraining column between each uppersample contact surface 226 and lower electrode contact surface 222.

System 200 may preferably connected with a pulse generator such tooperable to provide a desired pulse to samples held between pairs ofupper sample contact surfaces 226 and lower electrode contact surfaces222. Interlock fangs 232 and interlock spring contacts 234 preferablyprevent pulses from an associated pulse generator to be delivered toelectrode arrays 216 and 218 when the system is in an open or accessposition as shown. However, when upper body is moved into a closedposition, as shown in FIG. 9, interlock fangs 232 serve to complete thecircuitry required to deliver selected electric pulses to electrodearrays 216 and 218 necessary to electroporate samples held therebetween.

FIG. 9 shows eight sample electroporation system 200 shown in anoperational position. As shown, upper body 214 prevents physical accessto electrode arrays 216 and 218.

FIG. 10 shows electrode array 216. Electrode array 216 includes arraybody 217 with eight lower electrodes formed thereon. In alternateembodiments lower electrodes may be fixed to array body 217. Each lowerelectrode is preferably formed to have sample contact surface 222 havinga desired size and shape. Sample contact surface 222 in the presentembodiment is a flat, circular surface. Alternate sample contact surfacemay incorporate non-circular and non-flat shape.

Array body 217 of electrode array 216 includes interface lip 240extending generally perpendicular therefrom. Electrode body 217 furtherincludes removal tabs 238 to facilitate installation and removal ofarray 216.

FIG. 11 shows an eight sample electrode array 216 being interfaced withlower body 212. As shown, lower body includes interface slot 242 toallow electrode array to be conductively associated therewith. Interfacelip 240 is preferably aligned with and inserted into interface slot 242.Spring contacts within interface slot 242 conductively connect withinterface lip 240.

FIG. 12 shows an eight sample electroporation system 300 in anoperational position. As shown electroporation system 300 includes lowerbody (or “base” 312 and upper body 314 (or “top”). As shown in FIG. 13,which shows electroporation system 300 in an access position, lower body312 and upper body 314 are physically distinct and may be physicallyseparated. Lower body 312 includes electrode array 316 having eightelectrodes 322 (each with sample contact surfaces). Each electrode isphysically separated by insulated barriers 320. The insulated barriers(also referred to as “walls) serve to precisely space electrodes 322 andto maintain parallelism between corresponding electrodes.

Upper body 314 includes electrode array 318 that has electrodescorresponding to electrodes 322. Upper body 314 further includesinterlocking fangs 332 extending therefrom and space to interface withinterlock spring contacts 330. Interlocking fangs 332 and interlockspring contacts 330 function similarly to interlocking fangs 232 andinterlock spring contacts 234 discussed above. As shown in the presentembodiment, electrode arrays 316 and 318 are fixed to lower body 312 andupper body 314, respectively and are designed to be reused. In alternateembodiments, disposable arrays may be coupled lower body 312 and upperbody 314 and may incorporate features for easy insertion and removal.

A ninety-six sample electroporation system 400 is shown in an accessposition in FIG. 14 and in an operational position in FIG. 15. As shownelectroporation system 400 includes lower body (or “base” 412 and upperbody 414 (or “top”). Lower body 412 and upper body 414 are physicallydistinct and may be physically separated. Lower body 412 includeselectrode array 416 having ninety-six electrodes 422 (each with sample acontact surfaces). Lower body 412 and upper body 414 correspond toprecisely space electrodes 422 and to maintain parallelism with thecorresponding upper electrodes.

Upper body 414 includes electrode array 418 that has upper electrodes(not expressly shown) corresponding to electrodes 422. Upper body 414further includes interlocking fangs 432 as well as interlock springcontacts (not expressly shown) formed to mate with interlock fangs 432projecting from lower body 412. Interlocking fangs 432 and interlockspring contacts 430 function similarly to interlocking fangs 232 andinterlock spring contacts 234 discussed above. As shown in the presentembodiment, electrode arrays 416 and 418 are fixed to lower body 412 andupper body 414, respectively and may be reused or may be removed andreplaced.

Now referring to FIG. 16, an electroporation system 500 includes housing512 that generally includes lower body 514 and upper body 516 is shown.Lower body 514 and upper body 516 are both preferably constructed ofnonconductive materials. In the present embodiment, upper body 516 ispivotally connected to lower body 514 at pivot point 518 which allowsupper body 516 to rotate between a generally vertical access position,as shown, and a generally horizontal operational position, such as isshown in FIG. 2.

Electroporation system 500 further includes conductive slide mountingstructure 522 attached to lower body 514. Conductive slide mountingstructure 522 is preferably designed to mechanically and conductivelyinterface with a conductive slide such as electrode slide 540 as shownin FIG. 18. In the present embodiment conductive slide mountingstructure 522 includes a groove 526 formed to receive a conductive slide540. Groove 526 is formed between first side wall 528 and second sidewall 530. Groove 526 also includes an interface slot 524 formed toconductively interface with conductive slide 540. In preferredembodiments, interface slot 524 may include a spring contact forconductively interfacing with a conductive slide. The front side ofgroove 526 includes a rounded edge 532 to facilitate loading andunloading of slides thereon.

Upper housing 516 includes upper electrode 536 attached thereto whichmay be selectively removable for replacement or sanitization. Upperelectrode 536 preferably includes contact surface 538 (which may also bereferred to as an upper electrode contact surface). Upper electrodecontact surface 538 is preferably sized and shaped to correspond with acontact surface of an electroporation slide. In the present embodimentcontact surface 538 has a generally rectangular shape to correspond withthe generally rectangular contact surface area of electrode slide 540.

Now referring to FIG. 17, a conductive slide 540 is shown. Conductiveslide 540 includes base 542 having interface tab 544 extendingtherefrom. Interface tab 544 is preferably sized to insert withininterface slot 524 to allow a desired electric pulse to pass through theconductive portions of slide 540 and also to make a mechanicalconnection therewith. Slide 540 further includes ring element 548attached thereto. Ring element 548 defines the shape and size of contactsurface 550 (which may also be referred to as a lower electrode contactsurface) and further forms a well thereon for depositing a sample. Ringelement 548 may be secured onto slide 540 using any suitable attachmentor fastening method and may further be constructed of a nonconductivematerial.

Slide 540 may be used with any sample but is particularly applicable foruse with adherent cells that may be developed, grown, or otherwiseprocessed on the surface 550 of slide 540. Such processing may takeplace both before and/or after the electroporation of the sample. Insome operations, cells may be plated onto contact surface in normalgrowth media and cultured to allow time for cells to attach. Cells wouldthen be prepared for electroporation by first washing the cells insterile phosphate-buffered saline followed by the addition ofelectroporation buffer containing a transfectant (siRNA, other nucleicacid, etc.). After the applied electroporation event, cells would beallowed to rest and recover for a desired amount of time, in manyinstances five to twenty minutes. The buffer may then be removed andfresh media added to the cells. Cells may then be cultured for apredetermined period of time appropriate for the particular assay.

Base 542 may be a glass slide that includes a conductive layer 546formed on the top surface of the slide. In one embodiment, layer 546 isa conductive material such as indium-tin-oxide (ITO). In otherembodiments, layer 546 may be a gas permeable membrane such as aluminumoxide membrane filters.

FIG. 18 shows slide 540 installed within conductive slide mountingstructure 522. Slide mounting structure 522 interfaces with slide 540such that an electric pulse may be conducted to layer 546 and, in turn,to contact surface 550. In operation, a sample may be provided oncontact surface 550 and upper body may then be positioned such thatupper electrode contact surface 538 contacts the sample and ispositioned at a desired gap width. Layer 546 and electrode 536 arefurther in conductive connection with a pulse generator (as shown inFIG. 5) operable to provide a desired pulse for a desired duration.

Although the disclosed embodiments have been described in detail, itshould be understood that various changes, substitutions and alterationscan be made to the embodiments without departing from their spirit andscope.

1. A system for electroporating a sample comprising: a housing having alower body and an upper body; a first removable electrode having a firstsample contact surface, the first removable electrode coupled to thelower body; a second removable electrode having a second sample contactsurface, the second removable electrode coupled to the upper body; thefirst removable electrode and the second removable electrode positionedoperable to confine a surface tension constrained sample between thefirst sample contact surface and the second sample contact surface; andthe first removable electrode and the second removable electrodeoperable to receive an electric pulse from a pulse generator.
 2. Thesystem of claim 1 wherein the upper body further comprises an armassembly movable between: an operational position comprising the firstremovable electrode and the second removable electrode positionedoperable to confine a surface tension constrained sample between thefirst sample contact surface and the second sample contact surface; andan access position comprising the second removable electrode positionedaway from the first removable electrode.
 3. The system of claim 1further comprising a first replacement electrode operable to replace thefirst removable electrode and a second replacement electrode operable toreplace the second removable electrode.
 4. The system of claim 1 whereinthe first surface comprises a substantially flat surface and the secondsurface comprises a substantially flat surface.
 5. The system of claim 1wherein the first sample contact surface comprises a concave surface andthe second sample contact surface comprises a convex surface.
 6. Thesystem of claim 1 further comprising the first removable electrode andthe second removable electrode in communication with a pulse generator.7. The system of claim 6 further comprising a monitoring systemassociated with the pulse generator for monitoring at least oneparameter selected from the group comprising: voltage of pulse, durationof pulse, number of pulses and waveform of pulse.
 8. The system of claim1 further comprising the first removable electrode and the secondremovable electrode positioned to provide a gap width between 0.01millimeters and 10 millimeters.
 9. The system of claim 1 furthercomprising the first sample contact surface having a surface area sizedto hold a sample greater than approximately 10 microliters.
 10. Thesystem of claim 1 wherein the first surface and the second surface havea substantially circular shape having a diameter in the range ofapproximately two millimeters and approximately twelve millimeters. 11.The system of claim 1 wherein: the first removable electrode comprises alower electrode array having a plurality of lower electrodes, the firstremovable electrode array coupled to the lower body, each lowerelectrode having a sample contact surface; the second removableelectrode comprises an upper electrode array having a plurality of upperelectrodes, each upper electrode having a sample contact surface; theplurality of upper electrodes corresponding to the plurality of lowerelectrodes such that the lower electrode array and the upper electrodearray comprise a plurality of corresponding electrode pairs; and thesecond electrode array coupled to the upper body such that eachcorresponding electrode pair is disposed operable to confine a surfacetension constrained sample between the sample contact surface of eachlower electrode and the sample contact surface of each correspondingupper electrode sample contact surface.
 12. The system of claim 11wherein the upper body further comprises an arm assembly movablebetween: an operational position comprising the first removableelectrode and the second removable electrode positioned operable toconfine a plurality of surface tension constrained samples between theplurality of corresponding electrode pairs; and an access positioncomprising the second removable electrode positioned away from the firstremovable electrode.
 13. The system of claim 1 further comprising thefirst removable electrode and the second removable electrode operable toconduct an electric pulse from a pulse generator sized to electroporatea sample comprising at least one element provided for electroporation.14. The system of claim 13 wherein the at least one element comprises anucleic acid.
 15. The system of claim 13 wherein the at least oneelement comprises a protein.
 16. The system of claim 13 wherein the atleast one element comprises a biologically active agent.
 17. The systemof claim 13 wherein the at least one element comprises a siRNA.
 18. Thesystem of claim 13 wherein the at least one element comprises a mRNA.19. The system of claim 1 further comprising the first removableelectrode and the second removable electrode operable to conduct anelectric pulse from a pulse generator sized to electroporate a cellsample.
 20. The system of claim 19 wherein the cell sample comprises aprimary cell sample.
 21. An electrode array comprising: an electrodebase operable to conductively couple to an electroporation body; theelectrode base having a plurality of sample contact surfaces disposedthereon, the contact surfaces sized to hold an electroporation sample;and the plurality of sample contact surfaces operable to receive anelectric pulse from a pulse generator; and the plurality of samplecontact surfaces sized and disposed on the electrode base to correspondwith a plurality of sample contact surfaces associated with acorresponding electrode array.
 22. The electrode array of claim 21wherein the plurality of sample contact surfaces comprise a pluralitysubstantially flat contact surfaces.
 23. The electrode array of claim 21wherein the plurality of sample contact surfaces comprise a plurality ofconcave contact surfaces.
 24. The electrode array of claim 21 whereinthe plurality of sample contact surfaces comprise a plurality of convexcontact surfaces.
 25. The electrode array of claim 21 wherein theplurality of contact surfaces comprise a plurality of contact surfaceshaving a substantially circular shape having a diameter in a range ofapproximately two millimeters and approximately twelve millimeters. 26.A system for electroporating a sample comprising: a housing having alower body and an upper body; a first electrode array having a pluralityof lower sample contact surfaces, the first electrode array coupled tothe lower body; a second electrode array having a plurality of uppersample contact surfaces corresponding to the plurality of lower samplecontact surfaces, the second electrode array coupled to the upper body;the lower body and the upper body positioned operable to confine asurface tension constrained sample between each of the plurality oflower sample contact surfaces and each of the plurality of upper samplecontact surfaces; and the first electrode array and the second electrodearray operable to receive an electric pulse from a pulse generator. 27.The system of claim 26 wherein the upper body further comprises an armassembly movable between: an operational position comprising the lowerbody and the upper body positioned operable to confine a surface tensionconstrained sample between each of the plurality of lower sample contactsurfaces and each of the plurality of upper sample contact surfaces; andan access position comprising the lower body positioned away from theupper body.
 28. The system of claim 26 wherein the plurality of lowersample contact surfaces and the plurality of upper sample contactsurfaces comprises a substantially flat surfaces.
 29. The system ofclaim 26 wherein the plurality of lower sample contact surfaces compriseconcave surfaces and the plurality of upper sample contact surfacescomprises convex surfaces.
 30. The system of claim 26 further comprisingthe first electrode array and the second electrode array incommunication with a pulse generator.
 31. The system of claim 30 furthercomprising a monitoring system associated with the pulse generator formonitoring at least one parameter selected from the group comprising:voltage of pulse, duration of pulse, number of pulses and waveform ofpulse.
 32. The system of claim 26 further comprising the first removableelectrode and the second removable electrode positioned to provide a gapwidth between 0.01 millimeters and 10 millimeters.
 33. The system ofclaim 26 further comprising the each lower sample contact surface havinga surface area sized to hold a sample between approximately 10microliters and approximately 200 microliters.
 34. The system of claim26 further comprising each lower sample contact surface having asubstantially circular shape with a diameter in the range ofapproximately two millimeters and approximately twelve millimeters. 35.The system of claim 26 further comprising the first electrode array andthe second electrode array operable to conduct an electric pulse from apulse generator sized to electroporate a sample.
 36. The system of claim35 wherein the sample comprises siRNA.
 37. The system of claim 35wherein the sample comprises mRNA.
 38. The system of claim 26 furthercomprising the first electrode array and the second electrode arrayoperable to conduct an electric pulse from a pulse generator sized toelectroporate a cell sample.
 39. The system of claim 38 wherein the cellsample further comprises a primary cell sample.
 40. A method forelectroporating a sample comprising: positioning an upper body of anelectroporation system in an access position; depositing a sample on asample contact surface of a first electrode disposed in the lower bodyof the electroporation system; positioning the upper body in anoperational position such that the sample is confined between the lowercontact surface and an upper contact surface of a second electrodedisposed in the upper body; and sending an electric pulse between thelower electrode and the upper electrode.